Building codes for commercial buildings generally require fire barriers that prevent the combustion products of fire, e.g., heat, smoke and gases, from passing through building joints into adjoining areas. Joints in buildings, e.g., joints between walls, floors, walls and floors, perimeter joints and joints at the head of a wall (i.e., between a wall and a ceiling), include two structures that meet to define an opening. The opening can potentially provide a source of oxygen for a fire. Therefore, joint openings are usually filled with a fire retardant material, e.g., insulation or mineral wool, to provide a xe2x80x9cfire dam,xe2x80x9d and then sealed, e.g., with a caulk, putty or a sprayable coating, to provide a fire barrier.
The sealant applied to the joint is often flexible to accommodate joint movement due to building movement that may occur due to various forces including, e.g., loads, heat, wind and seismic factors. Such joints are often referred to as xe2x80x9cdynamic joints.xe2x80x9d Dynamic joints are generally linear openings in a building designed to allow for building movement. Examples of dynamic joints include joints within floors or walls, and joints between floors and walls. Dynamic joints are often referred to in the trade as xe2x80x9cconstruction joints,xe2x80x9d xe2x80x9csoft joints,xe2x80x9d xe2x80x9cexpansion joints,xe2x80x9d and xe2x80x9cseismic joints.xe2x80x9d A fire barrier for a dynamic joint generally needs to retain its resiliency over an extended period of time under dynamic conditions. During a fire condition, the joint is likely to be subject to even greater movement, thereby making it necessary that the fire barrier retain its integrity and prevent the migration of flame and smoke under such conditions.
In one aspect, the invention features a method of providing a fire barrier, where the method includes coating an opening in a structure with a composition that includes an elastomer, the composition being substantially free of volatile organic compounds and, when dry, exhibiting a tensile strength of from about 300 psi to about 1500 psi, at least about 600% elongation, a modulus of from about 200 psi to about 600 psi, and a tensile toughness of greater than 10 in-lb. In one embodiment, the method further includes spraying the composition on the structure and across the opening. In another embodiment, the method further includes propelling the composition from an aerosol container onto the structure and across the opening.
In other embodiments, the structure includes a joint that includes a first substrate and a second substrate, the opening being disposed between the first substrate and the second substrate. In some embodiments, the structure further includes a fire retardant component disposed within the opening.
In other embodiments, the method provides a fire barrier capable of passing at least one of Fire Test No. 1, Fire Test No. 2, and Fire Test No. 3. In some embodiments, the composition is capable of passing at least one test selected from the group consisting of Fire Test No. 1, Fire Test No. 2 and Fire Test No. 3, when installed in the fire rated construction of the test.
In another aspect, the invention features a method of providing a fire barrier that includes coating an opening in a structure with a composition that includes a carboxylated elastomer, the composition being water reducible and, when dry, exhibiting a toughness of at least about 20 in-lb. In one embodiment the composition, when dry, exhibits at least about 600% elongation. In other embodiments, the composition, when dry, exhibits from at least about 700% elongation. In some embodiments, the composition, when dry, exhibits a tensile strength of from about 300 psi to about 1500 psi. In another embodiment, the composition, when dry, exhibits a toughness of at least about 30 in-lb. In one embodiment, the elastomer is selected from the group consisting of polychloroprene, styrene butadiene rubber and mixtures thereof. In some embodiments, the composition is substantially free of volatile organic compounds.
In other aspects, the invention features a method of providing a fire barrier that includes coating an opening in a structure with a composition that includes a carboxylated elastomer, the composition being water reducible and, when dry, exhibiting a modulus of from about 200 psi to about 600 psi and a toughness of greater than 10 in-lb. In one embodiment, the composition exhibits a modulus of from about 200 psi to about 300 psi. In other embodiments, the composition, when dry, exhibits a toughness of at least about 30 in-lb.
In another aspect, the invention features a method of providing a fire barrier that includes coating an opening in a structure with a composition that includes a carboxylated elastomer, the composition being water reducible and, when dry, exhibiting a tensile strength of from about 300 psi to about 1500 psi and a toughness of greater than 10 in-lb. In one embodiment, the composition exhibits a modulus of from about 200 psi to about 600 psi. In other embodiments, the composition, when dry, exhibits a toughness of at least about 30 in-lb.
In other aspects, the invention features a device capable of spraying a composition, the device includes a chamber and an above-described composition.
In another aspect, the invention features an aerosol container according to an above-described device, wherein the container further includes a propellant, e.g., a fluorocarbon.
The composition is well suited for sealing joints in buildings. The composition, after drying, provides a good barrier to combustion products such as smoke, heat and gases. The dried composition also exhibits good resistance to a fire hose stream of water. The dried composition is also sufficiently flexible so as to maintain a seal around a joint that experiences movement, i.e., a dynamic joint. The composition is also water reducible, i.e., dispersible in water without visible coagulation or stringing, and can be washed away with tap water, which affords easy cleanup to the user. In addition, the composition can be formulated to be sprayable, e.g., from a pressurized aerosol container, an air sprayer, an airless sprayer, a hand pressurized sprayer such as a xe2x80x9cHudsonxe2x80x9d type garden sprayer (H.D. Hudson Mfg. Co., Hastings, Minn.) or a trigger sprayer, which facilitates ease of use and application.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.
The method of providing a fire barrier includes sealing an opening, e.g., a joint in a structure. The opening can be sealed by 1) coating a composition on the substrate(s) that defines the joint opening, as well as material within the opening, e.g., a fire retardant material (e.g., insulation or mineral wool), and 2) drying the composition to provide a seal that inhibits (more preferably prevents) the combustion products of fire from passing through the seal and the joint. The composition can be applied to all sides of the joint. The composition can be applied using a variety of techniques including, e.g., painting and spraying as described below.
The composition dries to form a film that, when tested at room temperature and after aging for 3 hours at 100xc2x0 C., exhibits a tensile strength of from about 2.067 MPa (300 psi) to about 10.335 MPa (1500 psi) (more preferably from about 2.067 MPa (300 psi) to about 4.134 MPa (600 psi)), greater than about 600% elongation (preferably at least about 700% elongation, most preferably at least about 1000% elongation), a modulus of from about 1.378 MPa (200 psi) to about 4.134 MPa (600 psi) (more preferably from about 1.378 MPa (200 psi) to about 2.067 MPa (300 psi)), and a tensile toughness of greater than 1.13 Joules (10 in-lb) (preferably greater than about 2.26 Joules (20 in-lb), more preferably greater than about 3.39 Joules (30 in-lb), most preferably greater than about 4.52 Joules (40 in-lb)).
Upon drying, the composition also exhibits good adhesion to building substrates including, e.g., gypsum wallboard (i.e., sheetrock), concrete mortar, steel, fire retardant substrates, e.g., insulation and mineral wool, and other materials that define and fill joints in buildings. Preferred compositions exhibit a 90xc2x0 peel strength, at break load, to concrete mortar of at least about 7 N/ln cm (4 lb/linear in), more preferably at least about 17.52 N/ln cm (10 lb/linear in.) when measured according to the 90xc2x0 Peel Adhesion Test Method set forth below. The dried composition preferably does not flow when exposed to elevated temperatures, i.e., temperatures above room temperature.
The composition also forms a film that is sufficiently flexible to accommodate movement of a fire-rated assembly. Preferably the composition meets the wind sway (at 500 cycles at 10 cycles/min) and thermal (at 500 cycles at 1 cycle/min) categories that are set forth in ASTM E 1399.
The composition is formulated to maintain the integrity of a fire-rated assembly. The composition is also formulated such that it can maintain its fire barrier properties after experiencing repeated compression and extension cycling. The composition can also withstand the forces exerted by a water stream from a fire hose under fire conditions. Preferably the composition passes the Fire Test and the Hose Stream Test of Underwriters Laboratories, Inc. Standard for Safety UTL 2079 Test for Fire Resistance of Building Joint Systems.
Preferred compositions are self-extinguishing, i.e., unable to sustain combustion without the addition of an external fuel source.
The liquid composition is water reducible and can be washed away with water without visible coagulating or stringing. Preferably the composition is infinitely miscible with water.
The liquid composition is formulated to have a viscosity suitable for the desired application method. Preferably the composition has a viscosity suitable for use in sprayers, e.g., airless sprayers, aerosol sprayers, hand pressurized sprayers and trigger sprayers. Preferably the composition has a viscosity of no greater than about 45 Pa*sec (45,000 cPs), more preferably from about 10 Pa*sec (10,000 cPs) to about 30 Pa*sec (30,000 cPs). For aerosol or hand pressurized sprayers, the viscosity is preferably from about 3 Pa*sec (3000 cPs) to about 5 Pa*sec (5,000 cPs), more preferably no greater than 4 Pa*sec (4,000 cPs).
The composition includes a latex that includes an elastomer, preferably a carboxylated elastomer. Examples of useful carboxylated elastomers include carboxylated polychloroprene (i.e., neoprene), carboxylated styrene butadiene rubber, carboxylated acrylonitrile, and combinations thereof.
Other useful elastomers include addition polymers derived from ethylenically unsaturated monomers, e.g., vinylacetate and acrylics, epoxy derived condensation polymers, urethanes, and carboxylated derivatives thereof, and combinations thereof.
The dried composition preferably includes carboxylated polychloroprene in an amount of from about 40% by weight to 100% by weight, more preferably from about 45% by weight to about 80% by weight, most preferably from about 55% by weight to about 75% by weight.
The composition may include an antioxidant. Examples of useful antioxidants include metal oxides, e.g., zinc oxide and magnesium oxide, hindered bisphenols, and hindered amine s. Preferably the amount of antioxidant present in the composition is from 0 to 5% by weight. Zinc oxide may also serve to provide ionic crosslinks among carboxylated polymer molecules in the dried film.
Other additives can be included in the composition including, e.g., antifoam agents, pigment, thickeners, antimicrobial agents, surfactants and combinations thereof
The composition is preferably substantially free of volatile organic compounds.
The composition can be formulated with a propellant to provide an aerosol formulation capable of being dispensed from an aerosol container. The propellant and the components of the composition are selected to provide a stable system (preferably a stable dispersion) that is free of coagulation, stringing, or a combination thereof, when dispensed from an aerosol container. Examples of useful propellants include fluorocarbons, hydrocarbons and mixtures thereof. Suitable fluorocarbon propellants include, e.g., HFC-152a, HFC-134, HFC-134a, and mixtures thereof. Suitable hydrocarbon propellants include, e.g., propane, butane, n-butane, isobutane, pentane, isopentane, neopentane and combinations thereof.
The composition can be coated on a substrate using a variety of methods including, e.g., painting and spraying, e.g., pressurized aerosol spraying, air spraying, airless spraying, hand pressurized spraying and trigger spraying. The composition is also suitable for packaging in a number of containers including, e.g., pressurized aerosol containers, e.g., cans and canisters, and drums.